First report of Lasiodiplodia theobromae (Pat.) Griffon & Maubl causing root rot and collar rot disease of physic nut (Jatropha curcas L.) in India P. Latha A , V. Prakasam A , A. Kamalakannan A , C. Gopalakrishnan A,C , T. Raguchander A , M. Paramathma B and R. Samiyappan A A Department of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore 641 003, Tamil Nadu, India. B Centre of Excellence in Biofuel, Agricultural Engineering College & Research Institute, TNAU, Coimbatore 641 003, Tamil Nadu, India. C Corresponding author. Email: pc_gopal@yahoo.co.in Abstract. Physic nut (Jatropha curcas), an important bio-fuel crop grown in the state of Tamil Nadu, India suffered heavy losses due to a root disease in 2007. The symptoms observed were yellowing, drooping and shedding of leaves, blackening and decaying of the collar region of the stem and rotting of the roots. Lasiodiplodia theobromae was isolated consistently from the diseased tissues of affected plants. Pathogenicity of L. theobromae was confirmed by artificial inoculations on 1-year-old plants. This is the first report of root rot and collar rot disease of physic nut in India. Physic nut (Jatropha curcas, Fam. Euphorbiaceae) is a drought- resistant shrub cultivated in Central and South America, South- east Asia, India and Africa (Schmook and Seralta-Peraza 1997). It is a multipurpose crop of significant economic importance as a biofuel. Moreover, parts of the shrub are used in traditional medicine and as raw material for pharmaceutical and cosmetic industries (Paramathma et al. 2006). In August–December 2007, physic nut grown in Coimbatore, Erode, Tirunelvelli, Thoothukudi, Virudhunagar, Karur, Dindigul and Thiruvallur districts of Tamil Nadu, India suffered heavy losses. The symptoms observed were yellowing, drooping and shedding of leaves (Fig. 1), blackening and decaying of the collar region of the stem and rotting of roots, followed by death of plants in most severe cases. Small to medium-sized black hard erumpent pycnidia were seen on the collar region. Infected roots and stems exhibited internal discolouration and browning of vascular regions (Fig. 2). Eighteen samples of infected stems and roots were used for isolations. A fungus was consistently isolated on potato dextrose agar (PDA) from the diseased collar and root regions. The same fungus was isolated from all 18 samples, and no other fungus was isolated from the infected roots and stems. After 4–5 days of incubation in PDA at 28  2  C with a 12-h photoperiod, the fungus initially produced white colonies, which later turned black (5–7 days). The mycelium was fast spreading, immersed, branched and septate. Shiny black pycnidia were produced on the medium surface after 7–8 days at the same culture conditions as above. Paraphyses were present interspersed with conidiogenous cells in the pycnidia. Conidia were initially unicellular, ellipsoidal, hyaline, thick-walled with granular content, and measuring 22.5  12.5 mm. Mature conidia were Fig. 1. Yellowing and wilting of an affected plant. CSIRO PUBLISHING www.publish.csiro.au/journals/apdn Australasian Plant Disease Notes, 2009, 4, 19–20 Ó Australasian Plant Pathology Society 2009 10.1071/DN09008 1833-928X/09/010019